Law of reciprocal proportions


The law of reciprocal proportions is one of the basic laws of stoichiometry. It relates the proportions in which elements combine across a number of different elements. It was first formulated by Jeremias Richter in 1791.
A simple statement of the law is:-
The acceptance of the law allowed tables of element equivalent weights to be drawn up. These equivalent weights were widely used by chemists in the 19th century.
The other laws of stoichiometry are the law of definite proportions and the law of multiple proportions.
The law of definite proportions refers to the fixed composition of any compound formed between element A and element B. The law of multiple proportions describes the stoichiometric relationship between two or more different compounds formed between element A and element B.

History

The law of reciprocal proportions was proposed in essence by Richter, following his determination of neutralisation ratios of metals with acids. In the early 19th century it was investigated by Berzelius, who formulated it as follows:
Later Jean Stas showed that within experimental error the stoichiometric laws were correct.